Encapsulated systems represent an important issue for the flavor and fragrance industry.
Encapsulated systems are designed so as to achieve two kinds of objectives. The first goal typically sought is related to the function of protection of the ingredients covered by such systems. In fact, these systems must be capable of protecting an active material there-encapsulated from different types of “aggressions” such as oxidation or moisture. The stabilization of these systems constitutes therefore a critical issue in the field.
Another objective always targeted for an encapsulated system consists in controlling in an appropriate way (depending on the final application) the release of the active ingredient or composition encapsulated. In particular, in the case where the active ingredient is volatile, it may be of much importance to sustain and control its release during a prolonged period of time.
The complexity of such systems, as well as the variety of applications there-relate, justify a constant need to improve encapsulated systems and processes for making them so as to obtain products which satisfy all the requirements needed, such as a good stability under certain use conditions or an optimized controlled release of the encapsulate.
The prior art and in particular the patent literature describes a large number of encapsulated systems prepared by way of extrusion methods. Extrusion methods typically rely on the use of carbohydrate matrix materials which are heated to a molten state and combined with an active ingredient, before extruding and quenching the extruded mass to form a glass which protects said ingredient. Typical products issued from these methods and used in the flavor industry are dry, granular delivery systems in which the active ingredient is a flavor uniformly distributed as droplets throughout a carbohydrate glass.
One significant example of the prior art disclosure in this field is U.S. Pat. No. 3,704,137 which describes an essential oil composition formed by mixing an oil with an antioxidant, separately mixing water, sucrose and hydrolysed cereal solids with DE below 20, emulsifying the two mixtures together, extruding the resulting mixture in the form of rods into a solvent, removing the excess solvent and finally adding an anti-caking agent.
Another pertinent example is that described in U.S. Pat. No. 4,610,890 and U.S. Pat. No. 4,707,367 which disclose a process for forming a stable, melt based and extruded, solid, essential oil flavor composition, as well as a product of this process. The melt to be extruded consists, in this particular case, in a matrix formed of an aqueous mixture of a sugar and a starch hydrolysate together with a selected emulsifier, said aqueous mixture being further blended with a selected quantity of essential oil flavor. The above-mentioned patents, and all the other prior art there-cited, are merely illustrative of the considerable volume of patent literature related to the fixation of flavour ingredients in various matrices and which, in essence, discloses the encapsulation of flavour materials in glass-like polymeric materials, in particular carbohydrate matrices.
A large variety of matrix components are disclosed in this prior art and play a part in the release process of these systems. In the case of systems based on the use of carbohydrate materials, said carbohydrates dissolve almost instantly in the presence of water, thus releasing the flavor into the aqueous environment. Complete dissolution and flavor liberation occur in less than 1 minute and may last up to 2 minutes, depending on the exact composition of the matrix.
Now, in applications where water is present, a better retention of a flavor within a particle may be needed. Similarly, the field of perfumery embraces many applications where a prolonged diffusion of the perfuming ingredient or composition through the particles may be desired.
Some methods to achieve those effects are known and generally consist in making particles with an insoluble surface (coacervation, coating with a fat). However, said techniques require an additional step (coating) and do not provide optimal results.
Now, the present invention offers a product with a retarded flavor or fragrance release in water, and which is an improvement of standard extrusion technology such as disclosed in the above-mentioned patent literature as well as in other documents cited below. In fact, we have now been able to realize a novel granular i.e. extruded system capable of controlling the release of an active ingredient, in particular in an aqueous environment. Said system is based on the use of agar agar in the matrix composition.
Amongst the large number of materials disclosed in the prior art as being potentially useful in matrix compositions of encapsulated systems, agar agar is often cited and used either as a coating material, or as a binder or granulating agent.
Agar agar is part of the family of hydrocolloids, also referred as gums. Hydrocolloids are long-chain high molecular weight polymers that disperse and hydrate in water to give a thickening and sometimes a gelling effect.
A large amount of the patent literature related to encapsulated systems cites agar agar as part of the possible encapsulation materials. For instance, WO 99/27798, which describes improved chewing gum formulations including sodium bicarbonate and Aspartame® in an encapsulated form, discloses agar agar in a list of coating ingredients, said list also comprising in particular dextrin, modified starch, acacia or maltodextrin. On the other hand, agar agar is also cited in some documents as being used as a granulating agent. In particular, U.S. Pat. No. 4,911,934, which also describes a chewing gum composition including encapsulated sweeteners and having an extended flavor release, discloses the use of agar agar as a granulating agent, capable of causing agglomeration or aggregation of the sweetening agent particles.
Therefore, agar agar has a widespread use in foods as stabilizer, thickener, humectant and surface finisher. Like many other colloids, agar agar also has film forming and bioadhesive properties. However, although other hydrocolloids are frequently cited in specific examples of the patent literature, agar agar only appears as part of the all encompassing list of gums, hydrocolloids, film forming agents and bioadhesives and is disclosed generally as a possible useful material, but not specifically exemplified.
Yet, we have now been able to establish that, in combination with a carbohydrate material and when used in far smaller amounts than those disclosed in the prior art, agar agar is a very useful matrix material and provides particularly advantageous effects on extruded systems, stabilising them in an aqueous environment and improving the retention of the active ingredient or composition there-encapsulated.